Disc drives are used for data storage in modem electronic products ranging from digital cameras to computers and network systems. Ordinarily, a disc drive includes a mechanical portion, or head disc assembly, and electronics in the form of a printed circuit board assembly mounted to an outer surface of the head disc assembly. The printed circuit board assembly controls functions of the head disc assembly and provides a communication interface between the disc drive and a host being serviced by the disc drive.
The head disc assembly has a disc with a recording surface rotated at a constant speed by a spindle motor assembly and an actuator assembly positionably controlled by a closed loop servo system. The actuator assembly supports a read/write head that writes data to and reads data from the recording surface.
The disc drive market continues to place pressure on the industry for disc drives with increased capacity at a lower cost per megabyte, higher rates of data throughput, and improved reliability.
As capacities increase and performance demands rise, disc drives become more susceptible to non-repeatable disturbances that occurred during the operation of the disc drive. Non-repeatable disturbances occurring at frequencies that imparted a resonance to the discs of a disc drive can cause the closed loop servo system to malfunction during track following operations or read/write errors during data transfer operations. Occurrences of either a servo system malfunction or read/write error directly impacts the overall performance of the disc drive.
Disc drives operating with a plurality of substantially identical discs, wherein each of the discs of the plurality of discs is responsive to substantially the same resonance frequencies heighten the opportunity for malfunction by the servo system or the occurrence of read/write errors during data transfer operations. The increase of opportunity for read/write errors results from appearance of coupling between discs resonating at the same frequencies. This coupling multiplies the number of disc resonances and increases the amplitude response at the resonances because discs support each other in closed resonating mode.
As such, challenges remain and a need persists for improvements in management of disc resonances for improved operational performance of the disc drive.